1 /* 2 * Copyright (C) 2003 Sistina Software Limited. 3 * Copyright (C) 2004-2005 Red Hat, Inc. All rights reserved. 4 * 5 * This file is released under the GPL. 6 */ 7 8 #include "dm.h" 9 #include "dm-path-selector.h" 10 #include "dm-hw-handler.h" 11 #include "dm-bio-list.h" 12 #include "dm-bio-record.h" 13 14 #include <linux/ctype.h> 15 #include <linux/init.h> 16 #include <linux/mempool.h> 17 #include <linux/module.h> 18 #include <linux/pagemap.h> 19 #include <linux/slab.h> 20 #include <linux/time.h> 21 #include <linux/workqueue.h> 22 #include <asm/atomic.h> 23 24 #define MESG_STR(x) x, sizeof(x) 25 26 /* Path properties */ 27 struct pgpath { 28 struct list_head list; 29 30 struct priority_group *pg; /* Owning PG */ 31 unsigned fail_count; /* Cumulative failure count */ 32 33 struct path path; 34 }; 35 36 #define path_to_pgpath(__pgp) container_of((__pgp), struct pgpath, path) 37 38 /* 39 * Paths are grouped into Priority Groups and numbered from 1 upwards. 40 * Each has a path selector which controls which path gets used. 41 */ 42 struct priority_group { 43 struct list_head list; 44 45 struct multipath *m; /* Owning multipath instance */ 46 struct path_selector ps; 47 48 unsigned pg_num; /* Reference number */ 49 unsigned bypassed; /* Temporarily bypass this PG? */ 50 51 unsigned nr_pgpaths; /* Number of paths in PG */ 52 struct list_head pgpaths; 53 }; 54 55 /* Multipath context */ 56 struct multipath { 57 struct list_head list; 58 struct dm_target *ti; 59 60 spinlock_t lock; 61 62 struct hw_handler hw_handler; 63 unsigned nr_priority_groups; 64 struct list_head priority_groups; 65 unsigned pg_init_required; /* pg_init needs calling? */ 66 unsigned pg_init_in_progress; /* Only one pg_init allowed at once */ 67 68 unsigned nr_valid_paths; /* Total number of usable paths */ 69 struct pgpath *current_pgpath; 70 struct priority_group *current_pg; 71 struct priority_group *next_pg; /* Switch to this PG if set */ 72 unsigned repeat_count; /* I/Os left before calling PS again */ 73 74 unsigned queue_io; /* Must we queue all I/O? */ 75 unsigned queue_if_no_path; /* Queue I/O if last path fails? */ 76 unsigned saved_queue_if_no_path;/* Saved state during suspension */ 77 78 struct work_struct process_queued_ios; 79 struct bio_list queued_ios; 80 unsigned queue_size; 81 82 struct work_struct trigger_event; 83 84 /* 85 * We must use a mempool of mpath_io structs so that we 86 * can resubmit bios on error. 87 */ 88 mempool_t *mpio_pool; 89 }; 90 91 /* 92 * Context information attached to each bio we process. 93 */ 94 struct mpath_io { 95 struct pgpath *pgpath; 96 struct dm_bio_details details; 97 }; 98 99 typedef int (*action_fn) (struct pgpath *pgpath); 100 101 #define MIN_IOS 256 /* Mempool size */ 102 103 static kmem_cache_t *_mpio_cache; 104 105 struct workqueue_struct *kmultipathd; 106 static void process_queued_ios(void *data); 107 static void trigger_event(void *data); 108 109 110 /*----------------------------------------------- 111 * Allocation routines 112 *-----------------------------------------------*/ 113 114 static struct pgpath *alloc_pgpath(void) 115 { 116 struct pgpath *pgpath = kmalloc(sizeof(*pgpath), GFP_KERNEL); 117 118 if (pgpath) { 119 memset(pgpath, 0, sizeof(*pgpath)); 120 pgpath->path.is_active = 1; 121 } 122 123 return pgpath; 124 } 125 126 static inline void free_pgpath(struct pgpath *pgpath) 127 { 128 kfree(pgpath); 129 } 130 131 static struct priority_group *alloc_priority_group(void) 132 { 133 struct priority_group *pg; 134 135 pg = kmalloc(sizeof(*pg), GFP_KERNEL); 136 if (!pg) 137 return NULL; 138 139 memset(pg, 0, sizeof(*pg)); 140 INIT_LIST_HEAD(&pg->pgpaths); 141 142 return pg; 143 } 144 145 static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti) 146 { 147 struct pgpath *pgpath, *tmp; 148 149 list_for_each_entry_safe(pgpath, tmp, pgpaths, list) { 150 list_del(&pgpath->list); 151 dm_put_device(ti, pgpath->path.dev); 152 free_pgpath(pgpath); 153 } 154 } 155 156 static void free_priority_group(struct priority_group *pg, 157 struct dm_target *ti) 158 { 159 struct path_selector *ps = &pg->ps; 160 161 if (ps->type) { 162 ps->type->destroy(ps); 163 dm_put_path_selector(ps->type); 164 } 165 166 free_pgpaths(&pg->pgpaths, ti); 167 kfree(pg); 168 } 169 170 static struct multipath *alloc_multipath(void) 171 { 172 struct multipath *m; 173 174 m = kmalloc(sizeof(*m), GFP_KERNEL); 175 if (m) { 176 memset(m, 0, sizeof(*m)); 177 INIT_LIST_HEAD(&m->priority_groups); 178 spin_lock_init(&m->lock); 179 m->queue_io = 1; 180 INIT_WORK(&m->process_queued_ios, process_queued_ios, m); 181 INIT_WORK(&m->trigger_event, trigger_event, m); 182 m->mpio_pool = mempool_create(MIN_IOS, mempool_alloc_slab, 183 mempool_free_slab, _mpio_cache); 184 if (!m->mpio_pool) { 185 kfree(m); 186 return NULL; 187 } 188 } 189 190 return m; 191 } 192 193 static void free_multipath(struct multipath *m) 194 { 195 struct priority_group *pg, *tmp; 196 struct hw_handler *hwh = &m->hw_handler; 197 198 list_for_each_entry_safe(pg, tmp, &m->priority_groups, list) { 199 list_del(&pg->list); 200 free_priority_group(pg, m->ti); 201 } 202 203 if (hwh->type) { 204 hwh->type->destroy(hwh); 205 dm_put_hw_handler(hwh->type); 206 } 207 208 mempool_destroy(m->mpio_pool); 209 kfree(m); 210 } 211 212 213 /*----------------------------------------------- 214 * Path selection 215 *-----------------------------------------------*/ 216 217 static void __switch_pg(struct multipath *m, struct pgpath *pgpath) 218 { 219 struct hw_handler *hwh = &m->hw_handler; 220 221 m->current_pg = pgpath->pg; 222 223 /* Must we initialise the PG first, and queue I/O till it's ready? */ 224 if (hwh->type && hwh->type->pg_init) { 225 m->pg_init_required = 1; 226 m->queue_io = 1; 227 } else { 228 m->pg_init_required = 0; 229 m->queue_io = 0; 230 } 231 } 232 233 static int __choose_path_in_pg(struct multipath *m, struct priority_group *pg) 234 { 235 struct path *path; 236 237 path = pg->ps.type->select_path(&pg->ps, &m->repeat_count); 238 if (!path) 239 return -ENXIO; 240 241 m->current_pgpath = path_to_pgpath(path); 242 243 if (m->current_pg != pg) 244 __switch_pg(m, m->current_pgpath); 245 246 return 0; 247 } 248 249 static void __choose_pgpath(struct multipath *m) 250 { 251 struct priority_group *pg; 252 unsigned bypassed = 1; 253 254 if (!m->nr_valid_paths) 255 goto failed; 256 257 /* Were we instructed to switch PG? */ 258 if (m->next_pg) { 259 pg = m->next_pg; 260 m->next_pg = NULL; 261 if (!__choose_path_in_pg(m, pg)) 262 return; 263 } 264 265 /* Don't change PG until it has no remaining paths */ 266 if (m->current_pg && !__choose_path_in_pg(m, m->current_pg)) 267 return; 268 269 /* 270 * Loop through priority groups until we find a valid path. 271 * First time we skip PGs marked 'bypassed'. 272 * Second time we only try the ones we skipped. 273 */ 274 do { 275 list_for_each_entry(pg, &m->priority_groups, list) { 276 if (pg->bypassed == bypassed) 277 continue; 278 if (!__choose_path_in_pg(m, pg)) 279 return; 280 } 281 } while (bypassed--); 282 283 failed: 284 m->current_pgpath = NULL; 285 m->current_pg = NULL; 286 } 287 288 static int map_io(struct multipath *m, struct bio *bio, struct mpath_io *mpio, 289 unsigned was_queued) 290 { 291 int r = 1; 292 unsigned long flags; 293 struct pgpath *pgpath; 294 295 spin_lock_irqsave(&m->lock, flags); 296 297 /* Do we need to select a new pgpath? */ 298 if (!m->current_pgpath || 299 (!m->queue_io && (m->repeat_count && --m->repeat_count == 0))) 300 __choose_pgpath(m); 301 302 pgpath = m->current_pgpath; 303 304 if (was_queued) 305 m->queue_size--; 306 307 if ((pgpath && m->queue_io) || 308 (!pgpath && m->queue_if_no_path)) { 309 /* Queue for the daemon to resubmit */ 310 bio_list_add(&m->queued_ios, bio); 311 m->queue_size++; 312 if ((m->pg_init_required && !m->pg_init_in_progress) || 313 !m->queue_io) 314 queue_work(kmultipathd, &m->process_queued_ios); 315 pgpath = NULL; 316 r = 0; 317 } else if (!pgpath) 318 r = -EIO; /* Failed */ 319 else 320 bio->bi_bdev = pgpath->path.dev->bdev; 321 322 mpio->pgpath = pgpath; 323 324 spin_unlock_irqrestore(&m->lock, flags); 325 326 return r; 327 } 328 329 /* 330 * If we run out of usable paths, should we queue I/O or error it? 331 */ 332 static int queue_if_no_path(struct multipath *m, unsigned queue_if_no_path, 333 unsigned save_old_value) 334 { 335 unsigned long flags; 336 337 spin_lock_irqsave(&m->lock, flags); 338 339 if (save_old_value) 340 m->saved_queue_if_no_path = m->queue_if_no_path; 341 else 342 m->saved_queue_if_no_path = queue_if_no_path; 343 m->queue_if_no_path = queue_if_no_path; 344 if (!m->queue_if_no_path && m->queue_size) 345 queue_work(kmultipathd, &m->process_queued_ios); 346 347 spin_unlock_irqrestore(&m->lock, flags); 348 349 return 0; 350 } 351 352 /*----------------------------------------------------------------- 353 * The multipath daemon is responsible for resubmitting queued ios. 354 *---------------------------------------------------------------*/ 355 356 static void dispatch_queued_ios(struct multipath *m) 357 { 358 int r; 359 unsigned long flags; 360 struct bio *bio = NULL, *next; 361 struct mpath_io *mpio; 362 union map_info *info; 363 364 spin_lock_irqsave(&m->lock, flags); 365 bio = bio_list_get(&m->queued_ios); 366 spin_unlock_irqrestore(&m->lock, flags); 367 368 while (bio) { 369 next = bio->bi_next; 370 bio->bi_next = NULL; 371 372 info = dm_get_mapinfo(bio); 373 mpio = info->ptr; 374 375 r = map_io(m, bio, mpio, 1); 376 if (r < 0) 377 bio_endio(bio, bio->bi_size, r); 378 else if (r == 1) 379 generic_make_request(bio); 380 381 bio = next; 382 } 383 } 384 385 static void process_queued_ios(void *data) 386 { 387 struct multipath *m = (struct multipath *) data; 388 struct hw_handler *hwh = &m->hw_handler; 389 struct pgpath *pgpath = NULL; 390 unsigned init_required = 0, must_queue = 1; 391 unsigned long flags; 392 393 spin_lock_irqsave(&m->lock, flags); 394 395 if (!m->queue_size) 396 goto out; 397 398 if (!m->current_pgpath) 399 __choose_pgpath(m); 400 401 pgpath = m->current_pgpath; 402 403 if ((pgpath && !m->queue_io) || 404 (!pgpath && !m->queue_if_no_path)) 405 must_queue = 0; 406 407 if (m->pg_init_required && !m->pg_init_in_progress) { 408 m->pg_init_required = 0; 409 m->pg_init_in_progress = 1; 410 init_required = 1; 411 } 412 413 out: 414 spin_unlock_irqrestore(&m->lock, flags); 415 416 if (init_required) 417 hwh->type->pg_init(hwh, pgpath->pg->bypassed, &pgpath->path); 418 419 if (!must_queue) 420 dispatch_queued_ios(m); 421 } 422 423 /* 424 * An event is triggered whenever a path is taken out of use. 425 * Includes path failure and PG bypass. 426 */ 427 static void trigger_event(void *data) 428 { 429 struct multipath *m = (struct multipath *) data; 430 431 dm_table_event(m->ti->table); 432 } 433 434 /*----------------------------------------------------------------- 435 * Constructor/argument parsing: 436 * <#multipath feature args> [<arg>]* 437 * <#hw_handler args> [hw_handler [<arg>]*] 438 * <#priority groups> 439 * <initial priority group> 440 * [<selector> <#selector args> [<arg>]* 441 * <#paths> <#per-path selector args> 442 * [<path> [<arg>]* ]+ ]+ 443 *---------------------------------------------------------------*/ 444 struct param { 445 unsigned min; 446 unsigned max; 447 char *error; 448 }; 449 450 #define ESTR(s) ("dm-multipath: " s) 451 452 static int read_param(struct param *param, char *str, unsigned *v, char **error) 453 { 454 if (!str || 455 (sscanf(str, "%u", v) != 1) || 456 (*v < param->min) || 457 (*v > param->max)) { 458 *error = param->error; 459 return -EINVAL; 460 } 461 462 return 0; 463 } 464 465 struct arg_set { 466 unsigned argc; 467 char **argv; 468 }; 469 470 static char *shift(struct arg_set *as) 471 { 472 char *r; 473 474 if (as->argc) { 475 as->argc--; 476 r = *as->argv; 477 as->argv++; 478 return r; 479 } 480 481 return NULL; 482 } 483 484 static void consume(struct arg_set *as, unsigned n) 485 { 486 BUG_ON (as->argc < n); 487 as->argc -= n; 488 as->argv += n; 489 } 490 491 static int parse_path_selector(struct arg_set *as, struct priority_group *pg, 492 struct dm_target *ti) 493 { 494 int r; 495 struct path_selector_type *pst; 496 unsigned ps_argc; 497 498 static struct param _params[] = { 499 {0, 1024, ESTR("invalid number of path selector args")}, 500 }; 501 502 pst = dm_get_path_selector(shift(as)); 503 if (!pst) { 504 ti->error = ESTR("unknown path selector type"); 505 return -EINVAL; 506 } 507 508 r = read_param(_params, shift(as), &ps_argc, &ti->error); 509 if (r) 510 return -EINVAL; 511 512 r = pst->create(&pg->ps, ps_argc, as->argv); 513 if (r) { 514 dm_put_path_selector(pst); 515 ti->error = ESTR("path selector constructor failed"); 516 return r; 517 } 518 519 pg->ps.type = pst; 520 consume(as, ps_argc); 521 522 return 0; 523 } 524 525 static struct pgpath *parse_path(struct arg_set *as, struct path_selector *ps, 526 struct dm_target *ti) 527 { 528 int r; 529 struct pgpath *p; 530 531 /* we need at least a path arg */ 532 if (as->argc < 1) { 533 ti->error = ESTR("no device given"); 534 return NULL; 535 } 536 537 p = alloc_pgpath(); 538 if (!p) 539 return NULL; 540 541 r = dm_get_device(ti, shift(as), ti->begin, ti->len, 542 dm_table_get_mode(ti->table), &p->path.dev); 543 if (r) { 544 ti->error = ESTR("error getting device"); 545 goto bad; 546 } 547 548 r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error); 549 if (r) { 550 dm_put_device(ti, p->path.dev); 551 goto bad; 552 } 553 554 return p; 555 556 bad: 557 free_pgpath(p); 558 return NULL; 559 } 560 561 static struct priority_group *parse_priority_group(struct arg_set *as, 562 struct multipath *m, 563 struct dm_target *ti) 564 { 565 static struct param _params[] = { 566 {1, 1024, ESTR("invalid number of paths")}, 567 {0, 1024, ESTR("invalid number of selector args")} 568 }; 569 570 int r; 571 unsigned i, nr_selector_args, nr_params; 572 struct priority_group *pg; 573 574 if (as->argc < 2) { 575 as->argc = 0; 576 ti->error = ESTR("not enough priority group aruments"); 577 return NULL; 578 } 579 580 pg = alloc_priority_group(); 581 if (!pg) { 582 ti->error = ESTR("couldn't allocate priority group"); 583 return NULL; 584 } 585 pg->m = m; 586 587 r = parse_path_selector(as, pg, ti); 588 if (r) 589 goto bad; 590 591 /* 592 * read the paths 593 */ 594 r = read_param(_params, shift(as), &pg->nr_pgpaths, &ti->error); 595 if (r) 596 goto bad; 597 598 r = read_param(_params + 1, shift(as), &nr_selector_args, &ti->error); 599 if (r) 600 goto bad; 601 602 nr_params = 1 + nr_selector_args; 603 for (i = 0; i < pg->nr_pgpaths; i++) { 604 struct pgpath *pgpath; 605 struct arg_set path_args; 606 607 if (as->argc < nr_params) 608 goto bad; 609 610 path_args.argc = nr_params; 611 path_args.argv = as->argv; 612 613 pgpath = parse_path(&path_args, &pg->ps, ti); 614 if (!pgpath) 615 goto bad; 616 617 pgpath->pg = pg; 618 list_add_tail(&pgpath->list, &pg->pgpaths); 619 consume(as, nr_params); 620 } 621 622 return pg; 623 624 bad: 625 free_priority_group(pg, ti); 626 return NULL; 627 } 628 629 static int parse_hw_handler(struct arg_set *as, struct multipath *m, 630 struct dm_target *ti) 631 { 632 int r; 633 struct hw_handler_type *hwht; 634 unsigned hw_argc; 635 636 static struct param _params[] = { 637 {0, 1024, ESTR("invalid number of hardware handler args")}, 638 }; 639 640 r = read_param(_params, shift(as), &hw_argc, &ti->error); 641 if (r) 642 return -EINVAL; 643 644 if (!hw_argc) 645 return 0; 646 647 hwht = dm_get_hw_handler(shift(as)); 648 if (!hwht) { 649 ti->error = ESTR("unknown hardware handler type"); 650 return -EINVAL; 651 } 652 653 r = hwht->create(&m->hw_handler, hw_argc - 1, as->argv); 654 if (r) { 655 dm_put_hw_handler(hwht); 656 ti->error = ESTR("hardware handler constructor failed"); 657 return r; 658 } 659 660 m->hw_handler.type = hwht; 661 consume(as, hw_argc - 1); 662 663 return 0; 664 } 665 666 static int parse_features(struct arg_set *as, struct multipath *m, 667 struct dm_target *ti) 668 { 669 int r; 670 unsigned argc; 671 672 static struct param _params[] = { 673 {0, 1, ESTR("invalid number of feature args")}, 674 }; 675 676 r = read_param(_params, shift(as), &argc, &ti->error); 677 if (r) 678 return -EINVAL; 679 680 if (!argc) 681 return 0; 682 683 if (!strnicmp(shift(as), MESG_STR("queue_if_no_path"))) 684 return queue_if_no_path(m, 1, 0); 685 else { 686 ti->error = "Unrecognised multipath feature request"; 687 return -EINVAL; 688 } 689 } 690 691 static int multipath_ctr(struct dm_target *ti, unsigned int argc, 692 char **argv) 693 { 694 /* target parameters */ 695 static struct param _params[] = { 696 {1, 1024, ESTR("invalid number of priority groups")}, 697 {1, 1024, ESTR("invalid initial priority group number")}, 698 }; 699 700 int r; 701 struct multipath *m; 702 struct arg_set as; 703 unsigned pg_count = 0; 704 unsigned next_pg_num; 705 706 as.argc = argc; 707 as.argv = argv; 708 709 m = alloc_multipath(); 710 if (!m) { 711 ti->error = ESTR("can't allocate multipath"); 712 return -EINVAL; 713 } 714 715 r = parse_features(&as, m, ti); 716 if (r) 717 goto bad; 718 719 r = parse_hw_handler(&as, m, ti); 720 if (r) 721 goto bad; 722 723 r = read_param(_params, shift(&as), &m->nr_priority_groups, &ti->error); 724 if (r) 725 goto bad; 726 727 r = read_param(_params + 1, shift(&as), &next_pg_num, &ti->error); 728 if (r) 729 goto bad; 730 731 /* parse the priority groups */ 732 while (as.argc) { 733 struct priority_group *pg; 734 735 pg = parse_priority_group(&as, m, ti); 736 if (!pg) { 737 r = -EINVAL; 738 goto bad; 739 } 740 741 m->nr_valid_paths += pg->nr_pgpaths; 742 list_add_tail(&pg->list, &m->priority_groups); 743 pg_count++; 744 pg->pg_num = pg_count; 745 if (!--next_pg_num) 746 m->next_pg = pg; 747 } 748 749 if (pg_count != m->nr_priority_groups) { 750 ti->error = ESTR("priority group count mismatch"); 751 r = -EINVAL; 752 goto bad; 753 } 754 755 ti->private = m; 756 m->ti = ti; 757 758 return 0; 759 760 bad: 761 free_multipath(m); 762 return r; 763 } 764 765 static void multipath_dtr(struct dm_target *ti) 766 { 767 struct multipath *m = (struct multipath *) ti->private; 768 769 flush_workqueue(kmultipathd); 770 free_multipath(m); 771 } 772 773 /* 774 * Map bios, recording original fields for later in case we have to resubmit 775 */ 776 static int multipath_map(struct dm_target *ti, struct bio *bio, 777 union map_info *map_context) 778 { 779 int r; 780 struct mpath_io *mpio; 781 struct multipath *m = (struct multipath *) ti->private; 782 783 if (bio_barrier(bio)) 784 return -EOPNOTSUPP; 785 786 mpio = mempool_alloc(m->mpio_pool, GFP_NOIO); 787 dm_bio_record(&mpio->details, bio); 788 789 map_context->ptr = mpio; 790 bio->bi_rw |= (1 << BIO_RW_FAILFAST); 791 r = map_io(m, bio, mpio, 0); 792 if (r < 0) 793 mempool_free(mpio, m->mpio_pool); 794 795 return r; 796 } 797 798 /* 799 * Take a path out of use. 800 */ 801 static int fail_path(struct pgpath *pgpath) 802 { 803 unsigned long flags; 804 struct multipath *m = pgpath->pg->m; 805 806 spin_lock_irqsave(&m->lock, flags); 807 808 if (!pgpath->path.is_active) 809 goto out; 810 811 DMWARN("dm-multipath: Failing path %s.", pgpath->path.dev->name); 812 813 pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path); 814 pgpath->path.is_active = 0; 815 pgpath->fail_count++; 816 817 m->nr_valid_paths--; 818 819 if (pgpath == m->current_pgpath) 820 m->current_pgpath = NULL; 821 822 queue_work(kmultipathd, &m->trigger_event); 823 824 out: 825 spin_unlock_irqrestore(&m->lock, flags); 826 827 return 0; 828 } 829 830 /* 831 * Reinstate a previously-failed path 832 */ 833 static int reinstate_path(struct pgpath *pgpath) 834 { 835 int r = 0; 836 unsigned long flags; 837 struct multipath *m = pgpath->pg->m; 838 839 spin_lock_irqsave(&m->lock, flags); 840 841 if (pgpath->path.is_active) 842 goto out; 843 844 if (!pgpath->pg->ps.type) { 845 DMWARN("Reinstate path not supported by path selector %s", 846 pgpath->pg->ps.type->name); 847 r = -EINVAL; 848 goto out; 849 } 850 851 r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path); 852 if (r) 853 goto out; 854 855 pgpath->path.is_active = 1; 856 857 m->current_pgpath = NULL; 858 if (!m->nr_valid_paths++ && m->queue_size) 859 queue_work(kmultipathd, &m->process_queued_ios); 860 861 queue_work(kmultipathd, &m->trigger_event); 862 863 out: 864 spin_unlock_irqrestore(&m->lock, flags); 865 866 return r; 867 } 868 869 /* 870 * Fail or reinstate all paths that match the provided struct dm_dev. 871 */ 872 static int action_dev(struct multipath *m, struct dm_dev *dev, 873 action_fn action) 874 { 875 int r = 0; 876 struct pgpath *pgpath; 877 struct priority_group *pg; 878 879 list_for_each_entry(pg, &m->priority_groups, list) { 880 list_for_each_entry(pgpath, &pg->pgpaths, list) { 881 if (pgpath->path.dev == dev) 882 r = action(pgpath); 883 } 884 } 885 886 return r; 887 } 888 889 /* 890 * Temporarily try to avoid having to use the specified PG 891 */ 892 static void bypass_pg(struct multipath *m, struct priority_group *pg, 893 int bypassed) 894 { 895 unsigned long flags; 896 897 spin_lock_irqsave(&m->lock, flags); 898 899 pg->bypassed = bypassed; 900 m->current_pgpath = NULL; 901 m->current_pg = NULL; 902 903 spin_unlock_irqrestore(&m->lock, flags); 904 905 queue_work(kmultipathd, &m->trigger_event); 906 } 907 908 /* 909 * Switch to using the specified PG from the next I/O that gets mapped 910 */ 911 static int switch_pg_num(struct multipath *m, const char *pgstr) 912 { 913 struct priority_group *pg; 914 unsigned pgnum; 915 unsigned long flags; 916 917 if (!pgstr || (sscanf(pgstr, "%u", &pgnum) != 1) || !pgnum || 918 (pgnum > m->nr_priority_groups)) { 919 DMWARN("invalid PG number supplied to switch_pg_num"); 920 return -EINVAL; 921 } 922 923 spin_lock_irqsave(&m->lock, flags); 924 list_for_each_entry(pg, &m->priority_groups, list) { 925 pg->bypassed = 0; 926 if (--pgnum) 927 continue; 928 929 m->current_pgpath = NULL; 930 m->current_pg = NULL; 931 m->next_pg = pg; 932 } 933 spin_unlock_irqrestore(&m->lock, flags); 934 935 queue_work(kmultipathd, &m->trigger_event); 936 return 0; 937 } 938 939 /* 940 * Set/clear bypassed status of a PG. 941 * PGs are numbered upwards from 1 in the order they were declared. 942 */ 943 static int bypass_pg_num(struct multipath *m, const char *pgstr, int bypassed) 944 { 945 struct priority_group *pg; 946 unsigned pgnum; 947 948 if (!pgstr || (sscanf(pgstr, "%u", &pgnum) != 1) || !pgnum || 949 (pgnum > m->nr_priority_groups)) { 950 DMWARN("invalid PG number supplied to bypass_pg"); 951 return -EINVAL; 952 } 953 954 list_for_each_entry(pg, &m->priority_groups, list) { 955 if (!--pgnum) 956 break; 957 } 958 959 bypass_pg(m, pg, bypassed); 960 return 0; 961 } 962 963 /* 964 * pg_init must call this when it has completed its initialisation 965 */ 966 void dm_pg_init_complete(struct path *path, unsigned err_flags) 967 { 968 struct pgpath *pgpath = path_to_pgpath(path); 969 struct priority_group *pg = pgpath->pg; 970 struct multipath *m = pg->m; 971 unsigned long flags; 972 973 /* We insist on failing the path if the PG is already bypassed. */ 974 if (err_flags && pg->bypassed) 975 err_flags |= MP_FAIL_PATH; 976 977 if (err_flags & MP_FAIL_PATH) 978 fail_path(pgpath); 979 980 if (err_flags & MP_BYPASS_PG) 981 bypass_pg(m, pg, 1); 982 983 spin_lock_irqsave(&m->lock, flags); 984 if (err_flags) { 985 m->current_pgpath = NULL; 986 m->current_pg = NULL; 987 } else if (!m->pg_init_required) 988 m->queue_io = 0; 989 990 m->pg_init_in_progress = 0; 991 queue_work(kmultipathd, &m->process_queued_ios); 992 spin_unlock_irqrestore(&m->lock, flags); 993 } 994 995 /* 996 * end_io handling 997 */ 998 static int do_end_io(struct multipath *m, struct bio *bio, 999 int error, struct mpath_io *mpio) 1000 { 1001 struct hw_handler *hwh = &m->hw_handler; 1002 unsigned err_flags = MP_FAIL_PATH; /* Default behavior */ 1003 1004 if (!error) 1005 return 0; /* I/O complete */ 1006 1007 if ((error == -EWOULDBLOCK) && bio_rw_ahead(bio)) 1008 return error; 1009 1010 if (error == -EOPNOTSUPP) 1011 return error; 1012 1013 spin_lock(&m->lock); 1014 if (!m->nr_valid_paths) { 1015 if (!m->queue_if_no_path) { 1016 spin_unlock(&m->lock); 1017 return -EIO; 1018 } else { 1019 spin_unlock(&m->lock); 1020 goto requeue; 1021 } 1022 } 1023 spin_unlock(&m->lock); 1024 1025 if (hwh->type && hwh->type->error) 1026 err_flags = hwh->type->error(hwh, bio); 1027 1028 if (mpio->pgpath) { 1029 if (err_flags & MP_FAIL_PATH) 1030 fail_path(mpio->pgpath); 1031 1032 if (err_flags & MP_BYPASS_PG) 1033 bypass_pg(m, mpio->pgpath->pg, 1); 1034 } 1035 1036 if (err_flags & MP_ERROR_IO) 1037 return -EIO; 1038 1039 requeue: 1040 dm_bio_restore(&mpio->details, bio); 1041 1042 /* queue for the daemon to resubmit or fail */ 1043 spin_lock(&m->lock); 1044 bio_list_add(&m->queued_ios, bio); 1045 m->queue_size++; 1046 if (!m->queue_io) 1047 queue_work(kmultipathd, &m->process_queued_ios); 1048 spin_unlock(&m->lock); 1049 1050 return 1; /* io not complete */ 1051 } 1052 1053 static int multipath_end_io(struct dm_target *ti, struct bio *bio, 1054 int error, union map_info *map_context) 1055 { 1056 struct multipath *m = (struct multipath *) ti->private; 1057 struct mpath_io *mpio = (struct mpath_io *) map_context->ptr; 1058 struct pgpath *pgpath = mpio->pgpath; 1059 struct path_selector *ps; 1060 int r; 1061 1062 r = do_end_io(m, bio, error, mpio); 1063 if (pgpath) { 1064 ps = &pgpath->pg->ps; 1065 if (ps->type->end_io) 1066 ps->type->end_io(ps, &pgpath->path); 1067 } 1068 if (r <= 0) 1069 mempool_free(mpio, m->mpio_pool); 1070 1071 return r; 1072 } 1073 1074 /* 1075 * Suspend can't complete until all the I/O is processed so if 1076 * the last path fails we must error any remaining I/O. 1077 * Note that if the freeze_bdev fails while suspending, the 1078 * queue_if_no_path state is lost - userspace should reset it. 1079 */ 1080 static void multipath_presuspend(struct dm_target *ti) 1081 { 1082 struct multipath *m = (struct multipath *) ti->private; 1083 1084 queue_if_no_path(m, 0, 1); 1085 } 1086 1087 /* 1088 * Restore the queue_if_no_path setting. 1089 */ 1090 static void multipath_resume(struct dm_target *ti) 1091 { 1092 struct multipath *m = (struct multipath *) ti->private; 1093 unsigned long flags; 1094 1095 spin_lock_irqsave(&m->lock, flags); 1096 m->queue_if_no_path = m->saved_queue_if_no_path; 1097 spin_unlock_irqrestore(&m->lock, flags); 1098 } 1099 1100 /* 1101 * Info output has the following format: 1102 * num_multipath_feature_args [multipath_feature_args]* 1103 * num_handler_status_args [handler_status_args]* 1104 * num_groups init_group_number 1105 * [A|D|E num_ps_status_args [ps_status_args]* 1106 * num_paths num_selector_args 1107 * [path_dev A|F fail_count [selector_args]* ]+ ]+ 1108 * 1109 * Table output has the following format (identical to the constructor string): 1110 * num_feature_args [features_args]* 1111 * num_handler_args hw_handler [hw_handler_args]* 1112 * num_groups init_group_number 1113 * [priority selector-name num_ps_args [ps_args]* 1114 * num_paths num_selector_args [path_dev [selector_args]* ]+ ]+ 1115 */ 1116 static int multipath_status(struct dm_target *ti, status_type_t type, 1117 char *result, unsigned int maxlen) 1118 { 1119 int sz = 0; 1120 unsigned long flags; 1121 struct multipath *m = (struct multipath *) ti->private; 1122 struct hw_handler *hwh = &m->hw_handler; 1123 struct priority_group *pg; 1124 struct pgpath *p; 1125 unsigned pg_num; 1126 char state; 1127 1128 spin_lock_irqsave(&m->lock, flags); 1129 1130 /* Features */ 1131 if (type == STATUSTYPE_INFO) 1132 DMEMIT("1 %u ", m->queue_size); 1133 else if (m->queue_if_no_path) 1134 DMEMIT("1 queue_if_no_path "); 1135 else 1136 DMEMIT("0 "); 1137 1138 if (hwh->type && hwh->type->status) 1139 sz += hwh->type->status(hwh, type, result + sz, maxlen - sz); 1140 else if (!hwh->type || type == STATUSTYPE_INFO) 1141 DMEMIT("0 "); 1142 else 1143 DMEMIT("1 %s ", hwh->type->name); 1144 1145 DMEMIT("%u ", m->nr_priority_groups); 1146 1147 if (m->next_pg) 1148 pg_num = m->next_pg->pg_num; 1149 else if (m->current_pg) 1150 pg_num = m->current_pg->pg_num; 1151 else 1152 pg_num = 1; 1153 1154 DMEMIT("%u ", pg_num); 1155 1156 switch (type) { 1157 case STATUSTYPE_INFO: 1158 list_for_each_entry(pg, &m->priority_groups, list) { 1159 if (pg->bypassed) 1160 state = 'D'; /* Disabled */ 1161 else if (pg == m->current_pg) 1162 state = 'A'; /* Currently Active */ 1163 else 1164 state = 'E'; /* Enabled */ 1165 1166 DMEMIT("%c ", state); 1167 1168 if (pg->ps.type->status) 1169 sz += pg->ps.type->status(&pg->ps, NULL, type, 1170 result + sz, 1171 maxlen - sz); 1172 else 1173 DMEMIT("0 "); 1174 1175 DMEMIT("%u %u ", pg->nr_pgpaths, 1176 pg->ps.type->info_args); 1177 1178 list_for_each_entry(p, &pg->pgpaths, list) { 1179 DMEMIT("%s %s %u ", p->path.dev->name, 1180 p->path.is_active ? "A" : "F", 1181 p->fail_count); 1182 if (pg->ps.type->status) 1183 sz += pg->ps.type->status(&pg->ps, 1184 &p->path, type, result + sz, 1185 maxlen - sz); 1186 } 1187 } 1188 break; 1189 1190 case STATUSTYPE_TABLE: 1191 list_for_each_entry(pg, &m->priority_groups, list) { 1192 DMEMIT("%s ", pg->ps.type->name); 1193 1194 if (pg->ps.type->status) 1195 sz += pg->ps.type->status(&pg->ps, NULL, type, 1196 result + sz, 1197 maxlen - sz); 1198 else 1199 DMEMIT("0 "); 1200 1201 DMEMIT("%u %u ", pg->nr_pgpaths, 1202 pg->ps.type->table_args); 1203 1204 list_for_each_entry(p, &pg->pgpaths, list) { 1205 DMEMIT("%s ", p->path.dev->name); 1206 if (pg->ps.type->status) 1207 sz += pg->ps.type->status(&pg->ps, 1208 &p->path, type, result + sz, 1209 maxlen - sz); 1210 } 1211 } 1212 break; 1213 } 1214 1215 spin_unlock_irqrestore(&m->lock, flags); 1216 1217 return 0; 1218 } 1219 1220 static int multipath_message(struct dm_target *ti, unsigned argc, char **argv) 1221 { 1222 int r; 1223 struct dm_dev *dev; 1224 struct multipath *m = (struct multipath *) ti->private; 1225 action_fn action; 1226 1227 if (argc == 1) { 1228 if (!strnicmp(argv[0], MESG_STR("queue_if_no_path"))) 1229 return queue_if_no_path(m, 1, 0); 1230 else if (!strnicmp(argv[0], MESG_STR("fail_if_no_path"))) 1231 return queue_if_no_path(m, 0, 0); 1232 } 1233 1234 if (argc != 2) 1235 goto error; 1236 1237 if (!strnicmp(argv[0], MESG_STR("disable_group"))) 1238 return bypass_pg_num(m, argv[1], 1); 1239 else if (!strnicmp(argv[0], MESG_STR("enable_group"))) 1240 return bypass_pg_num(m, argv[1], 0); 1241 else if (!strnicmp(argv[0], MESG_STR("switch_group"))) 1242 return switch_pg_num(m, argv[1]); 1243 else if (!strnicmp(argv[0], MESG_STR("reinstate_path"))) 1244 action = reinstate_path; 1245 else if (!strnicmp(argv[0], MESG_STR("fail_path"))) 1246 action = fail_path; 1247 else 1248 goto error; 1249 1250 r = dm_get_device(ti, argv[1], ti->begin, ti->len, 1251 dm_table_get_mode(ti->table), &dev); 1252 if (r) { 1253 DMWARN("dm-multipath message: error getting device %s", 1254 argv[1]); 1255 return -EINVAL; 1256 } 1257 1258 r = action_dev(m, dev, action); 1259 1260 dm_put_device(ti, dev); 1261 1262 return r; 1263 1264 error: 1265 DMWARN("Unrecognised multipath message received."); 1266 return -EINVAL; 1267 } 1268 1269 /*----------------------------------------------------------------- 1270 * Module setup 1271 *---------------------------------------------------------------*/ 1272 static struct target_type multipath_target = { 1273 .name = "multipath", 1274 .version = {1, 0, 4}, 1275 .module = THIS_MODULE, 1276 .ctr = multipath_ctr, 1277 .dtr = multipath_dtr, 1278 .map = multipath_map, 1279 .end_io = multipath_end_io, 1280 .presuspend = multipath_presuspend, 1281 .resume = multipath_resume, 1282 .status = multipath_status, 1283 .message = multipath_message, 1284 }; 1285 1286 static int __init dm_multipath_init(void) 1287 { 1288 int r; 1289 1290 /* allocate a slab for the dm_ios */ 1291 _mpio_cache = kmem_cache_create("dm_mpath", sizeof(struct mpath_io), 1292 0, 0, NULL, NULL); 1293 if (!_mpio_cache) 1294 return -ENOMEM; 1295 1296 r = dm_register_target(&multipath_target); 1297 if (r < 0) { 1298 DMERR("%s: register failed %d", multipath_target.name, r); 1299 kmem_cache_destroy(_mpio_cache); 1300 return -EINVAL; 1301 } 1302 1303 kmultipathd = create_workqueue("kmpathd"); 1304 if (!kmultipathd) { 1305 DMERR("%s: failed to create workqueue kmpathd", 1306 multipath_target.name); 1307 dm_unregister_target(&multipath_target); 1308 kmem_cache_destroy(_mpio_cache); 1309 return -ENOMEM; 1310 } 1311 1312 DMINFO("dm-multipath version %u.%u.%u loaded", 1313 multipath_target.version[0], multipath_target.version[1], 1314 multipath_target.version[2]); 1315 1316 return r; 1317 } 1318 1319 static void __exit dm_multipath_exit(void) 1320 { 1321 int r; 1322 1323 destroy_workqueue(kmultipathd); 1324 1325 r = dm_unregister_target(&multipath_target); 1326 if (r < 0) 1327 DMERR("%s: target unregister failed %d", 1328 multipath_target.name, r); 1329 kmem_cache_destroy(_mpio_cache); 1330 } 1331 1332 EXPORT_SYMBOL_GPL(dm_pg_init_complete); 1333 1334 module_init(dm_multipath_init); 1335 module_exit(dm_multipath_exit); 1336 1337 MODULE_DESCRIPTION(DM_NAME " multipath target"); 1338 MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>"); 1339 MODULE_LICENSE("GPL"); 1340